Ain't that the truth.
The approval side of things is probably a secondary issue to the original post (arguably the approval should be first :rolleyes: ) as it was the style of dwelling that was being put forward for comment and we have all studiously ignored that. I imagine that Maupatree is now thoroughly dejected :( .
Just on the "Tiny House" it actually has to be on wheels as in trailer mounted to qualify, but that is in the US and it can be up to semi trailer size. There is a height limitation too, which I think is around 4 metres. However that is in the US or Canada, but I mention it as it is possible that, depending on your location and council regulations that there may be a classification of a non permanent dwelling: Not much different to having a caravan in your backyard really. Again, and I am sure there is a queue behind me waiting to emphasise the need to verify all this, you would need to check with the council.
On the design of the house itself, it looks fine. There is a limit to what you can do with a small rectangular space and include what we regard as essential. Much of the appeal comes from the internal innovations (although the tricky bits sometimes contribute hugely to the cost). Most small house builders use the area beneath a staircase for cupboard storage for example. Can you face the houses North, both to take advantage of solar passive aspects and also for solar power if you wish the buildings to be self sufficient?
As with all houses the external "look" will be very important too. Just recently I have been bombarded with small house designs from Pinterest. Google and Facebook are of course other avenues for ideas. There is an Aussie (Bryce)who presents a series of videos on these types of homes, although it is based in Canada.
YouTube
Regards
Paul